#include <iostream>

using namespace std;

extern "C" {
void print_matrix_(double *mat, int *row, int *col);
}

int main() {
  double a[3][2]{1, 2, 3, 4, 5, 6};
  int row{3}, col{2};
  print_matrix_(&a[0][0], &row, &col);
  return 0;
}